The present invention relates to the art of interactive image-guided surgery. It finds particular application in conjunction with the planning stage of minimally invasive stereotactic surgery performed in CT imaging systems using guide devices to orient surgical tools such as biopsy probes or the like and will be described with particular reference thereto. It is to be appreciated, however, that the invention is also applicable to a wide range of imaging equipment and minimally invasive stereotactic surgical procedures including, for example, ultrasonic and magnetic resonance imaging devices and surgery performed using those devices.
Heretofore, several systems have been proposed combining mechanical arm type mechanisms together with human anatomy imaging devices for performing certain interventional surgical procedures such as, for example, the placement of catheters, drainage tubes, biopsy probes, or the like, within a patient's body. U.S. Pat. No. 5,142,930 teaches a mechanical arm device associated with an imaging system generating one or more images of a patient's anatomy and displaying those images on a screen. A computer is used to track the location of a surgical tool connected to the mechanical arm as the arm is moved through physical space. The computer performs a transforming rotation of the physical space to the image space in order to cause the display device to show the location of the surgical tool within the patient's image space. Position feedback devices are arranged on the mechanical arm for tracking the end tip of a tool on the arm relative to the position of fiducial implants disposed on or in the patient's body.
One disadvantage of the above system, however, is that the interventionist is not provided with a plurality of alternative views of the target within the patient. It would be desirable to simultaneously display views of the target within the patient, the entry point of a real or "virtual" needle on the patient's skin, and the trajectory of the virtual or biopsy needle therebetween. A frameless stereotactic CT scanner with a virtual needle co-axial with a surgical planning instrument and displayed on a monitor in the scanner room would greatly improve the planning stages of image-guided interventional procedures. A virtual needle that is displayed through multiple planes extending through a patient's image data volume set would provide an interventionist with an enhanced understanding of the path between the entry point and the target for the avoidance of damage to arteries or the like and obstructions such as bone.
U.S. Pat. No. 5,622,170 teaches a surgical apparatus for determining the position and orientation of an invasive portion of a surgical probe within a patient's body. A computer associated with that system determines the position and orientation of the invasive portion of the surgical tool by correlating the position of the tool relative to a predetermined coordinate system with a position of a model of the patient's body defined in relation to the predetermined coordinate system. During use of the above device, however, the interventionist is presented with only a single slice view of the position of the tool tip within a patient's body image.
It would be desirable to perform image-guided minimally invasive stereotactic surgical planning procedures with the advantage of multiple views of the path of a virtual needle defining a trajectory from an entry point on a patient's skin to a target image within the patient's body. In addition, it would be desirable to provide an automatic transformation between a surgical planning device in a localizer space and a patient image data set in image space so that the position of the surgical planning device is displayed as a virtual needle within the image of the patient. To best assist interventionists in positioning surgical instrument guide devices, the virtual needle is displayed on multiple screen portions of a display monitor or the like located in the scan room. It would also be desirable to provide a knob or other mechanism such as a manual slider for use by an interventionist to "extend" and "retract" the virtual needle in the multiple displays to quickly and easily chart various approach angles and orientations for planning interventional procedures.
An apparatus capable of determining desired coordinates in an image for use in either functional stereotactic or morphological procedures is taught in U.S. Pat. Nos. 5,398,684 and 5,099,846. The desired coordinates may include, for example, an entry point, a target or placement point, and a trajectory of a probe or the like. According to those patents, a surgeon can determine an optimum probe implantation trajectory using either one of a pair of equivalent methods. In the first method, the entry point of the probe is designated by "tacking" it on the image. A target point on another scanner image slice is selected and the coordinates of the two points are then used to determine a probe's spatial trajectory. In the second method, the trajectory of the probe is defined by entering the probe's angles according to the design of a stereotactic frame. A target point on one image slice is chosen. Next, the angles of the probes spatial interception with that point are entered into a computer. This defines the probe's spatial trajectory.
FIGS. 4, 6, and 8 illustrate sagittal and transverse axial views of a simulated probe trajectory and positioning regarding a tumor in a patient's brain. The views have limited utility because they are not updated simultaneously with movement of a surgical planning device over a patient's body such as by an interventionist using the planning device to manually search for an optimum needle insertion path.
It would be desirable to provide an imaging device with a set of virtual needle displays for planning image-guided interventional procedures. Preferably, the "length" of the virtual needle is manually adjustable by the interventionist using a knob or slide mechanism within reach of a surgical planning device on the end of a stereotactic mechanical arm.
The present invention provides new and improved methods and apparatus for planning image-guided interventional procedures which overcome the above-referenced problems and others.